Ultra-low loss bending resistant few-mode hollow core anti-resonant fiber with nested elliptical tubes

Abstract

A novel hollow core anti-resonant fiber with glass-sheet conjoined nested elliptical tubes is proposed and investigated numerically. The elliptical tubes are introduced to original HC-ANF with glass-sheet conjoined cladding, achieving ultra-low loss bending resistant few-mode transmission. Results shows that the proposed fiber with elliptical tubes exhibits lower high-order mode loss and better bending characteristics compared to that with circular tubes due to fact that elliptical tube cladding has a smaller effective air region, which effectively reduces the coupling between higher-order mode in air core and air mode in cladding. At the same time, the elliptical structure has greater negative curvature that makes high-order mode and silica mode have lower overlap. The proposed fiber with optimized parameters can support seven core mode groups, of which the minimum fundamental mode loss is 6.5 × 10^-4 dB/km and maximum LP₄₁ loss is 0.095 dB/km. An outstanding bending property is also proved in our proposed fiber as it can support five core mode groups when bending radius is 2 cm with a minimum fundamental mode loss of 0.001 dB/km and a maximum LP₃₁ loss of 1 dB/km.